Topband: Response to W8JI's comments about using a K2AV foldedcounterpoise at VK6VZ

[Tom W8JI]

I wonder.....Is there is a simple way to compare the field strength of an 
FCP with my current NON dense and uniform ground system, and draw reasonably 
accurate conclusions about efficiency improvements >>>

Sure. You can probably determine ground wave changes in a vertically 
polarized radiator with a simple test, if you wanted to do the work. Since 
you wouldn't know the baseline performance all you really could say is if it 
is better or worse than what you had.

Which brings me back to my general statement that a large change isn't so 
much about how perfect new systems are, as how bad our old systems were. :-)

I can tell you from direct experience at my house that near field effects on 
160 meters were noticeable at 300 feet, were barely noticeable at 600 feet, 
and were not measureable at 1500 feet. This was with an instrument that 
resolves 100th's of a dB, and is accurate in tenths over the signal level 
range. This is based on data acquired while attempting to null my 
transmitter out of receive antennas, (bottom of page at 
http://www.w8ji.com/antenna_coupling.htm) but would apply to pattern 
measurements.

This effect was with a large directional transmitting array, so it would be 
reasonable to expect a smaller array to require less distance. Based on 
measurements, 500 feet distance should be pretty safe.

It does not require absolute field intensity measurements if you only want 
to look at change. I primarily use two <$100 instruments here for playing. 
One is a Sierra 303B portable level meter, and the other less portable unit 
is an HP3586C.

I built small loop antennas for the 303B and calibrated them against a 
rental FSM.

I have also used fixed wire antennas that I installed out in the woods when 
I did not need an absolute level.

Having a portable selective level meter is worth it's weight in gold if you 
do antenna work. I use the HP3586C to look at signal levels here in the 
house. This lets me check gain and F/R of various antennas. It is far more 
accurate than spectrum analyzers and S meters. The HP will do averages, so 
it is great for testing transmitting antennas while listening to distant 
signals on them, like using W1AW to compare two transmitting antennas on 
skywave. I think I paid around $50 on eBay for it.

73 Tom